Design Method of Tangential Gradient Thermal Spraying Coating for Complex Profile Workpieces

1. A design method of tangential gradient thermal spraying coating for a centrifugal compressor impeller, the method comprising: determining an impact angle of erosion particles along a surface of the centrifugal compressor impeller according to a structure of the centrifugal compressor impeller and predetermined working conditions of the centrifugal compressor impeller; selecting an erosion-resistant coating material comprising a brittle material and a ductile material according to a service condition requirement of the centrifugal compressor impeller; spraying the selected erosion-resistant coating material to the centrifugal compressor impeller and conducting an erosion test on the centrifugal compressor impeller that had the selected erosion-resistant coating material sprayed to it so as to provide an erosion-resistant coating on the centrifugal compressor impeller, to obtain a relation among the impact angle, ductile-brittle ratio and erosion rate of the erosion-resistant coating; based on the impact angle of erosion particles along a surface of the centrifugal compressor impeller determined above, optimizing the obtained relation between the ductile-brittle ratio of the erosion-resistant coating and the impact angle to obtain a minimized average value of the erosion rate of the erosion-resistant coating for different positions on the centrifugal compressor impeller with different impact angles, with the relation among the impact angle, the ductile-brittle ratio and the erosion rate as a constraint condition, with the impact angles corresponding to points on the surface of the centrifugal compressor impeller as a position constraint, and a polynomial equation of the ductile-brittle ratio with respect to the impact angle being set as a continuity constraint of the ductile-brittle ratio of the erosion-resistant coating; and determining a corresponding relation between the ductile-brittle ratio of the erosion-resistant coating and surface location on the centrifugal compressor impeller utilizing the minimized average value of the erosion rate, and performing thermal spraying on the surface of the centrifugal compressor impeller utilizing the determined relation between the ductile-brittle ratio of the erosion-resistant coating and surface location of the centrifugal compressor impeller, wherein the erosion test comprises compounding the brittle material and the ductile material from the selected erosion-resistant coating material in different mixing ratios to obtain the erosion-resistant coating material, performing spraying on the centrifugal compressor impeller, designing a multi-factor erosion test by using an orthogonal test method to obtain test data of the impact angle, the ductile-brittle ratio and the erosion rate, and performing fitting to obtain a relation curve.

2. The design method of claim 1 , wherein the determining of the impact angle of erosion particles along a surface of the centrifugal compressor impeller comprises obtaining a model of the impeller, defining gas phase boundary conditions and particle boundary conditions, and performing simulation analysis to determine the impact angle of the erosion particles along the surface of the centrifugal compressor impeller.

3. The design method of claim 1 , wherein in the selection step, the service condition requirement comprises a coating performance requirement, a binding property of the erosion-resistant coating and a material of the centrifugal compressor impeller.

4. The design method of claim 1 , wherein the ductile-brittle ratio represents the mass ratio of ductile material to the total mass of ductile and brittle material.

5. The design method of claim 1 , wherein, thermal spraying is performed on the surface of the centrifugal compressor impeller by employing dual-channel powder feeder, the powder feeding quantity of which is adjustable in real time to achieve ductile-brittle ratio control.